It seems that the delayed indexing is ignored when changing the section of a content.
Steps to reproduce:
1) Deactivate all cronjobs on the server
2) Activate delayed indexing in site.ini
3) Create a new content object and publish it (nothing will be indexed to solr yet)
4) Search for some string on the object => no result
5) Edit the same content object and change the section. Any section will do. Just push the "Set" button
6) Search for your object => It will show up in the search results